| 摘要 |
PURPOSE:To execute the optimum evaluation with respect to variation noises by providing not only a noise level detecting system but also a detecting system for deriving an equivalent noise level by dividing the sum total of an energy of an input signal within a measuring time, by the measuring time. CONSTITUTION:A recording pen 5 of a driving part 4 can be operated by switching a noise level detecting system A and an equivalent noise level detecting system B by a switch S1, and an output of a logarithmic converting circuit 3 of the detecting system A is inputted to a subtracting circuit 15 through an exponent correcting circuit 9 of the detecting system B, an inverse logarithmic converting circuit 10, an integration circuit 11 and a logarithmic converting circuit 12. Also, a voltage of a constant-current power source 13 is inputted to the circuit 15 through a capacitor C, a logarithmic converting circuit 14, and an equivalent noise level is calculated by subtracting an outpuf of the circuit 14 from an output of the circuit 12, and outputted to the driving part 4 through the switch S1. |
